Final answer:
After undergoing a laboratory study to assess cardiopulmonary function, the client is most likely experiencing hypoxemia.
Step-by-step explanation:
After undergoing a laboratory study to assess cardiopulmonary function, the client is most likely experiencing a. Hypoxemia.
Hypoxemia refers to lower-than-normal levels of oxygen in the blood. In the provided information, the PA found that Barbara has hypoxemia - a lower-than-normal level of oxygen in the blood, which is suggestive of pneumonia. Pneumonia is a condition where the lungs fill with mucus, leading to a decrease in oxygen levels.
Therefore, the correct answer is a. Hypoxemia.